<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>圆角</title>

  <style>
    .div1 {
      width: 200px;
      height: 50vw;
      background-color: pink;
      border-radius: 10vw;
      border-radius: 1vw 3vw 5vw 10vw;
    }

    .div2 {
      width: 50vw;
      height: 50vw;
      background-color: orange;

      /* 正方形尺寸的50%为正圆 */
      border-radius: 50%;
    }

    .div3 {
      width: 60vw;
      height: 20vw;
      background-color: green;
      /* 长方形短边尺寸的一半为胶囊状圆角 */
      border-radius: 10vw;
    }
  </style>

</head>
<body>
  <div class="div1">圆角</div>
  <div class="div2">正圆</div>
  <div class="div3">胶囊</div>
</body>
</html>